The city is easing up on its rigid promotion criteria for students in grades 3 to 8 amid fear that too many kids will bomb the much harder state tests this spring.

In a letter to principals and parents, Schools Chancellor Dennis Walcott said only kids who score in the bottom 10 percent or so on the new math or English exams will be recommended for retention and summer school.

In past years, all students who scored at the lowest level of 1 on a 4-point scale on either exam were relegated to summer school. If they failed to improve, they were held back a grade.

Walcott said the city would focus on how many questions kids get right rather than on their overall performance levels to determine summer school assignment.

He added that the city would align its promotion criteria to the higher standards — known as Common Core — over time, rather than doing it abruptly this year.

“They can’t flunk everybody. They can’t afford to flunk everybody [because] they can’t afford to send all the kids to summer school,” said Leonie Haimson, director of Class Size Matters.

She called the DOE’s decision to ease up on its strict promotion requirements “reasonable,” given the harder test content.

“ I don’t think you pull the rug out from under people — that would be truly unfair to families and to kids to do that,” she said. “If you’re going to have high stakes at all with these tests, you have to try to maintain some kind of consistency in the way you’re deciding who passes and who fails.”